Ethyl 2-(4-methyl­benzo­yl)-2,3-dihydro-1H-indene-2-carboxyl­ate

Xiang, J.; Hu, T.; Wang, J.

doi:10.1107/S1600536813005801

organic compounds

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ISSN: 2056-9890

Volume 69| Part 4| April 2013| Page o504

doi:10.1107/S1600536813005801

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Ethyl 2-(4-methylbenzoyl)-2,3-dihydro-1H-indene-2-carboxylate

Jiachen Xiang,^a Tingting Hu ^a and Jungang Wang ^a ^*

^aKey Laboratory of Pesticides and Chemical Biology of the Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China
^*Correspondence e-mail: qwjgq@163.com

(Received 29 December 2012; accepted 28 February 2013; online 6 March 2013)

The title compound, C₂₀H₂₀O₃, contains two fused rings with a quaternary carbon centre connecting p-toluoyl and ethoxycarbonyl groups. The dihedral angle between the fused benzene ring and the three-C-atom plane (derived from O=C—C—C=O) is 82.5 (4)°, whereas the dihedral angle between the planes of the benzene rings is 53.4 (2)°. In the crystal, molecules are linked via C—H⋯O_ester hydrogen bonds, forming chains propagating along [010].

Related literature

For the preparation and crystal engineering studies of the title compound, see: Singh & Paul (2006 ); Wang & Wu (2012 ).

Experimental

Crystal data

C₂₀H₂₀O₃
M_r = 308.37
Monoclinic, P 2₁ /c
a = 8.1957 (14) Å
b = 6.1287 (10) Å
c = 32.995 (5) Å
β = 93.014 (3)°
V = 1655.0 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 298 K
0.12 × 0.10 × 0.10 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1997 ) T_min = 0.990, T_max = 0.992
11945 measured reflections
3241 independent reflections
2482 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.049
wR(F²) = 0.187
S = 1.09
3241 reflections
210 parameters
H-atom parameters constrained
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯O1ⁱ	0.93	2.60	3.357 (3)	139
Symmetry code: (i) $[-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT(Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536813005801/gg2108sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813005801/gg2108Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813005801/gg2108Isup3.cml

checkCIF report

Comment top

The title molecule (I)(Fig.1) was synthesized in a mixture of 1,4-dibromo-2,3- bis(bromomethyl)benzene (1.0 mmol), ethyl 3-oxo-3-(p-tolyl)propanoate (1.0 mmol) and Cs₂CO₃ (2 mmol) in DMSO (5 ml). The mixture was stirred at 40° for 30 min until almost full conversion of the substrates by TLC analysis. The resulting mixture was dropped into 100 ml 1 M HCl (aq) and extracted with EtOAc 3 times (3 times 50 ml). The organic extract was dried with Na₂SO₄, filtered and concentrated. The crude product was purified by column chromatography on silica gel (eluent: petroleum ether/EtOAc=50/1) to afford the product as a white solid.

Related literature top

For the preparation and crystal engineering studies of the title compound, see: Singh & Paul (2006); Wang & Wu (2012).

Experimental top

The title compound was synthesized according to the reported method (Singh et al.; 2006 and Wang et al.; 2012). The ethyl 3-oxo-3-(p-tolyl)propanoate reacts with 1,2-bis(halomethyl)benzene to obtain the title compound via a two-step C-alkylation process. Crystals of (I) suitable for X-ray diffraction were grown by slow evaporation of a acetic ether solution of the title compound (I) at 293 K.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT(Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. A view of (I), showing the atom-labelling scheme, with displacement ellipsoids drawn at the 30% probalility level.

Ethyl 2-(4-methylbenzoyl)-2,3-dihydro-1H-indene-2-carboxylate top

Crystal data top

C₂₀H₂₀O₃	F(000) = 656
M_r = 308.37	D_x = 1.238 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3624 reflections
a = 8.1957 (14) Å	θ = 2.5–24.5°
b = 6.1287 (10) Å	µ = 0.08 mm⁻¹
c = 32.995 (5) Å	T = 298 K
β = 93.014 (3)°	Block, colourless
V = 1655.0 (5) Å³	0.12 × 0.10 × 0.10 mm
Z = 4

Data collection top

Bruker APEXII CCD diffractometer	3241 independent reflections
Radiation source: fine-focus sealed tube	2482 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
ϕ and ω scans	θ_max = 26.0°, θ_min = 1.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	h = −10→10
T_min = 0.990, T_max = 0.992	k = −7→7
11945 measured reflections	l = −40→36

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.187	H-atom parameters constrained
S = 1.09	w = 1/[σ²(F_o²) + (0.1176P)² + 0.1336P] where P = (F_o² + 2F_c²)/3
3241 reflections	(Δ/σ)_max = 0.008
210 parameters	Δρ_max = 0.27 e Å⁻³
0 restraints	Δρ_min = −0.25 e Å⁻³

Crystal data top

C₂₀H₂₀O₃	V = 1655.0 (5) Å³
M_r = 308.37	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.1957 (14) Å	µ = 0.08 mm⁻¹
b = 6.1287 (10) Å	T = 298 K
c = 32.995 (5) Å	0.12 × 0.10 × 0.10 mm
β = 93.014 (3)°

Data collection top

Bruker APEXII CCD diffractometer	3241 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	2482 reflections with I > 2σ(I)
T_min = 0.990, T_max = 0.992	R_int = 0.025
11945 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.049	0 restraints
wR(F²) = 0.187	H-atom parameters constrained
S = 1.09	Δρ_max = 0.27 e Å⁻³
3241 reflections	Δρ_min = −0.25 e Å⁻³
210 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.7866 (3)	0.2221 (4)	0.25704 (6)	0.0666 (6)
H1	0.8421	0.2668	0.2809	0.080*
C2	0.8114 (3)	0.0156 (4)	0.24231 (7)	0.0693 (6)
H2	0.8860	−0.0765	0.2559	0.083*
C3	0.7266 (2)	−0.0567 (3)	0.20748 (6)	0.0555 (5)
H3	0.7424	−0.1972	0.1978	0.067*
C4	0.6182 (2)	0.0832 (3)	0.18736 (5)	0.0463 (4)
C5	0.5970 (2)	0.2939 (3)	0.20139 (5)	0.0452 (4)
C6	0.6805 (2)	0.3627 (3)	0.23682 (6)	0.0552 (5)
H6	0.6647	0.5027	0.2467	0.066*
C7	0.4828 (3)	0.4205 (3)	0.17361 (7)	0.0626 (6)
H7A	0.5406	0.5355	0.1602	0.075*
H7B	0.3963	0.4854	0.1885	0.075*
C8	0.5092 (3)	0.0359 (3)	0.15049 (7)	0.0655 (6)
H8A	0.4358	−0.0840	0.1556	0.079*
H8B	0.5732	−0.0015	0.1276	0.079*
C9	0.4114 (2)	0.2508 (3)	0.14203 (6)	0.0514 (5)
C10	0.2314 (3)	0.2265 (3)	0.14927 (6)	0.0555 (5)
C11	−0.0233 (3)	0.4180 (4)	0.14107 (7)	0.0726 (7)
H11A	−0.0434	0.4237	0.1698	0.087*
H11B	−0.0798	0.2922	0.1293	0.087*
C12	−0.0820 (3)	0.6211 (5)	0.12057 (9)	0.0863 (8)
H12A	−0.0303	0.7449	0.1336	0.129*
H12B	−0.1983	0.6324	0.1222	0.129*
H12C	−0.0554	0.6173	0.0926	0.129*
C13	0.4316 (2)	0.3270 (3)	0.09827 (6)	0.0516 (5)
C14	0.3593 (2)	0.1945 (3)	0.06402 (6)	0.0513 (5)
C15	0.3657 (3)	0.2784 (4)	0.02492 (7)	0.0676 (6)
H15	0.4123	0.4147	0.0212	0.081*
C16	0.3042 (3)	0.1633 (5)	−0.00819 (7)	0.0791 (7)
H16	0.3093	0.2236	−0.0340	0.095*
C17	0.2350 (3)	−0.0398 (5)	−0.00395 (7)	0.0705 (7)
C18	0.2282 (3)	−0.1239 (4)	0.03492 (7)	0.0665 (6)
H18	0.1819	−0.2607	0.0385	0.080*
C19	0.2881 (2)	−0.0102 (3)	0.06837 (6)	0.0578 (5)
H19	0.2811	−0.0703	0.0941	0.069*
C20	0.1698 (4)	−0.1689 (6)	−0.04011 (8)	0.1051 (11)
H20A	0.2398	−0.2916	−0.0442	0.158*
H20B	0.1664	−0.0777	−0.0638	0.158*
H20C	0.0616	−0.2196	−0.0354	0.158*
O1	0.1677 (3)	0.0787 (3)	0.16597 (5)	0.0896 (6)
O2	0.15098 (16)	0.4028 (2)	0.13532 (4)	0.0625 (4)
O3	0.5094 (2)	0.4910 (3)	0.09153 (5)	0.0775 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0753 (13)	0.0748 (15)	0.0488 (11)	−0.0053 (11)	−0.0071 (9)	−0.0038 (10)
C2	0.0733 (13)	0.0787 (15)	0.0548 (12)	0.0152 (12)	−0.0078 (10)	0.0051 (11)
C3	0.0662 (12)	0.0488 (11)	0.0516 (11)	0.0107 (9)	0.0038 (9)	0.0000 (8)
C4	0.0530 (9)	0.0411 (9)	0.0452 (9)	0.0012 (7)	0.0056 (7)	−0.0007 (7)
C5	0.0496 (9)	0.0402 (9)	0.0465 (10)	−0.0029 (7)	0.0097 (7)	−0.0031 (7)
C6	0.0675 (11)	0.0487 (11)	0.0502 (11)	−0.0103 (9)	0.0109 (9)	−0.0092 (8)
C7	0.0749 (13)	0.0380 (10)	0.0738 (14)	0.0074 (9)	−0.0077 (10)	−0.0111 (9)
C8	0.0928 (15)	0.0363 (10)	0.0649 (13)	0.0133 (9)	−0.0206 (11)	−0.0072 (9)
C9	0.0586 (10)	0.0358 (9)	0.0589 (11)	0.0047 (8)	−0.0059 (8)	−0.0017 (8)
C10	0.0712 (12)	0.0477 (11)	0.0480 (10)	−0.0093 (9)	0.0066 (9)	0.0021 (8)
C11	0.0517 (11)	0.1032 (19)	0.0637 (13)	−0.0118 (11)	0.0122 (9)	−0.0123 (13)
C12	0.0489 (12)	0.108 (2)	0.1017 (19)	0.0111 (12)	0.0005 (11)	−0.0099 (16)
C13	0.0441 (9)	0.0453 (10)	0.0659 (12)	0.0038 (8)	0.0074 (8)	0.0053 (9)
C14	0.0455 (9)	0.0539 (11)	0.0550 (11)	0.0080 (8)	0.0078 (7)	0.0051 (8)
C15	0.0675 (12)	0.0726 (14)	0.0641 (13)	0.0099 (11)	0.0151 (10)	0.0132 (11)
C16	0.0814 (15)	0.104 (2)	0.0525 (13)	0.0238 (15)	0.0096 (11)	0.0089 (13)
C17	0.0571 (11)	0.0984 (18)	0.0555 (13)	0.0277 (12)	−0.0020 (9)	−0.0150 (12)
C18	0.0634 (12)	0.0707 (14)	0.0649 (13)	0.0048 (10)	−0.0021 (9)	−0.0147 (11)
C19	0.0625 (11)	0.0587 (12)	0.0521 (11)	0.0014 (9)	0.0013 (8)	0.0008 (9)
C20	0.097 (2)	0.146 (3)	0.0700 (16)	0.0411 (19)	−0.0142 (14)	−0.0384 (17)
O1	0.1113 (14)	0.0733 (11)	0.0858 (13)	−0.0225 (10)	0.0211 (10)	0.0235 (9)
O2	0.0509 (8)	0.0652 (9)	0.0725 (9)	0.0009 (6)	0.0132 (6)	0.0094 (7)
O3	0.0783 (10)	0.0644 (9)	0.0909 (12)	−0.0230 (8)	0.0139 (9)	0.0072 (8)

Geometric parameters (Å, º) top

C1—C6	1.372 (3)	C11—C12	1.484 (4)
C1—C2	1.374 (3)	C11—H11A	0.9700
C1—H1	0.9300	C11—H11B	0.9700
C2—C3	1.384 (3)	C12—H12A	0.9600
C2—H2	0.9300	C12—H12B	0.9600
C3—C4	1.379 (3)	C12—H12C	0.9600
C3—H3	0.9300	C13—O3	1.216 (2)
C4—C5	1.385 (2)	C13—C14	1.489 (3)
C4—C8	1.499 (3)	C14—C15	1.392 (3)
C5—C6	1.389 (3)	C14—C19	1.395 (3)
C5—C7	1.493 (3)	C15—C16	1.374 (4)
C6—H6	0.9300	C15—H15	0.9300
C7—C9	1.564 (3)	C16—C17	1.378 (4)
C7—H7A	0.9700	C16—H16	0.9300
C7—H7B	0.9700	C17—C18	1.386 (3)
C8—C9	1.559 (3)	C17—C20	1.506 (3)
C8—H8A	0.9700	C18—C19	1.374 (3)
C8—H8B	0.9700	C18—H18	0.9300
C9—C10	1.514 (3)	C19—H19	0.9300
C9—C13	1.535 (3)	C20—H20A	0.9600
C10—O1	1.195 (2)	C20—H20B	0.9600
C10—O2	1.335 (3)	C20—H20C	0.9600
C11—O2	1.454 (2)

C6—C1—C2	120.55 (19)	O2—C11—H11A	110.3
C6—C1—H1	119.7	C12—C11—H11A	110.3
C2—C1—H1	119.7	O2—C11—H11B	110.3
C1—C2—C3	120.7 (2)	C12—C11—H11B	110.3
C1—C2—H2	119.6	H11A—C11—H11B	108.6
C3—C2—H2	119.6	C11—C12—H12A	109.5
C4—C3—C2	118.89 (19)	C11—C12—H12B	109.5
C4—C3—H3	120.6	H12A—C12—H12B	109.5
C2—C3—H3	120.6	C11—C12—H12C	109.5
C3—C4—C5	120.47 (17)	H12A—C12—H12C	109.5
C3—C4—C8	127.69 (17)	H12B—C12—H12C	109.5
C5—C4—C8	111.81 (16)	O3—C13—C14	120.20 (19)
C4—C5—C6	119.98 (18)	O3—C13—C9	120.44 (18)
C4—C5—C7	111.40 (16)	C14—C13—C9	119.33 (16)
C6—C5—C7	128.61 (17)	C15—C14—C19	117.6 (2)
C1—C6—C5	119.33 (19)	C15—C14—C13	117.97 (19)
C1—C6—H6	120.3	C19—C14—C13	124.38 (17)
C5—C6—H6	120.3	C16—C15—C14	121.1 (2)
C5—C7—C9	105.30 (15)	C16—C15—H15	119.4
C5—C7—H7A	110.7	C14—C15—H15	119.4
C9—C7—H7A	110.7	C15—C16—C17	121.3 (2)
C5—C7—H7B	110.7	C15—C16—H16	119.4
C9—C7—H7B	110.7	C17—C16—H16	119.4
H7A—C7—H7B	108.8	C16—C17—C18	117.8 (2)
C4—C8—C9	105.09 (15)	C16—C17—C20	121.6 (3)
C4—C8—H8A	110.7	C18—C17—C20	120.5 (3)
C9—C8—H8A	110.7	C19—C18—C17	121.6 (2)
C4—C8—H8B	110.7	C19—C18—H18	119.2
C9—C8—H8B	110.7	C17—C18—H18	119.2
H8A—C8—H8B	108.8	C18—C19—C14	120.5 (2)
C10—C9—C13	109.40 (15)	C18—C19—H19	119.8
C10—C9—C8	112.61 (16)	C14—C19—H19	119.8
C13—C9—C8	110.23 (16)	C17—C20—H20A	109.5
C10—C9—C7	107.08 (16)	C17—C20—H20B	109.5
C13—C9—C7	111.68 (16)	H20A—C20—H20B	109.5
C8—C9—C7	105.78 (15)	C17—C20—H20C	109.5
O1—C10—O2	123.5 (2)	H20A—C20—H20C	109.5
O1—C10—C9	126.9 (2)	H20B—C20—H20C	109.5
O2—C10—C9	109.51 (15)	C10—O2—C11	118.56 (16)
O2—C11—C12	106.95 (18)

C6—C1—C2—C3	−1.9 (3)	C8—C9—C10—O2	−169.98 (16)
C1—C2—C3—C4	1.0 (3)	C7—C9—C10—O2	74.16 (19)
C2—C3—C4—C5	1.2 (3)	C10—C9—C13—O3	124.95 (19)
C2—C3—C4—C8	−177.0 (2)	C8—C9—C13—O3	−110.7 (2)
C3—C4—C5—C6	−2.5 (3)	C7—C9—C13—O3	6.6 (2)
C8—C4—C5—C6	176.01 (18)	C10—C9—C13—C14	−56.9 (2)
C3—C4—C5—C7	176.28 (18)	C8—C9—C13—C14	67.4 (2)
C8—C4—C5—C7	−5.2 (2)	C7—C9—C13—C14	−175.30 (15)
C2—C1—C6—C5	0.6 (3)	O3—C13—C14—C15	−8.0 (3)
C4—C5—C6—C1	1.6 (3)	C9—C13—C14—C15	173.84 (16)
C7—C5—C6—C1	−176.9 (2)	O3—C13—C14—C19	170.76 (19)
C4—C5—C7—C9	7.9 (2)	C9—C13—C14—C19	−7.4 (3)
C6—C5—C7—C9	−173.47 (17)	C19—C14—C15—C16	−0.1 (3)
C3—C4—C8—C9	178.54 (18)	C13—C14—C15—C16	178.77 (18)
C5—C4—C8—C9	0.2 (2)	C14—C15—C16—C17	−0.4 (3)
C4—C8—C9—C10	−112.09 (18)	C15—C16—C17—C18	0.5 (3)
C4—C8—C9—C13	125.43 (18)	C15—C16—C17—C20	−179.0 (2)
C4—C8—C9—C7	4.5 (2)	C16—C17—C18—C19	0.0 (3)
C5—C7—C9—C10	112.94 (18)	C20—C17—C18—C19	179.4 (2)
C5—C7—C9—C13	−127.31 (17)	C17—C18—C19—C14	−0.5 (3)
C5—C7—C9—C8	−7.4 (2)	C15—C14—C19—C18	0.6 (3)
C13—C9—C10—O1	135.3 (2)	C13—C14—C19—C18	−178.23 (18)
C8—C9—C10—O1	12.4 (3)	O1—C10—O2—C11	0.7 (3)
C7—C9—C10—O1	−103.5 (2)	C9—C10—O2—C11	−176.98 (16)
C13—C9—C10—O2	−47.0 (2)	C12—C11—O2—C10	−176.51 (19)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···O3	0.97	2.28	2.762 (3)	110
C8—H8A···O1	0.97	2.45	2.883 (3)	107
C1—H1···O1ⁱ	0.93	2.60	3.357 (3)	139

Symmetry code: (i) −x+1, y+1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₂₀H₂₀O₃
M_r	308.37
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	8.1957 (14), 6.1287 (10), 32.995 (5)
β (°)	93.014 (3)
V (Å³)	1655.0 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.12 × 0.10 × 0.10

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1997)
T_min, T_max	0.990, 0.992
No. of measured, independent and observed [I > 2σ(I)] reflections	11945, 3241, 2482
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.187, 1.09
No. of reflections	3241
No. of parameters	210
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.27, −0.25

Computer programs: APEX2 (Bruker, 2004), SAINT(Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···O1ⁱ	0.93	2.60	3.357 (3)	139

Symmetry code: (i) −x+1, y+1/2, −z+1/2.

Acknowledgements

The authors are grateful to the Central China Normal University for financial support and thank Dr Xiang-Gao Meng for the X-ray data collection.

References

Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin,USA. Google Scholar
Sheldrick, G. M. (1997). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Singh, P. & Paul, K. (2006). J. Heterocycl. Chem. 43, 607–611. CrossRef CAS Google Scholar
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